Rotor of rotary-electric machine

ABSTRACT

In a rotor of a rotary-electric machine, in order to improve a cooling performance of a rotor winding, in a rotor winding on an end portion of the rotor in an axial direction, the rotor winding being held by a retaining ring of the rotor winding formed by laminating a plurality of conductors in slots of a rotor iron core extending in an axial direction and having a plurality of slots formed at predetermined intervals in a peripheral direction, ventilation channels through which cooling air flows are formed in the surfaces of the conductors along a longitudinal direction. The ventilation channels have air inlet holes which guide the cooling air and exhaust holes which exhaust the cooling air, the conductors provided with the ventilation channels which are formed in the surfaces of the conductors along the longitudinal direction and through which the cooling air flows are laminated to constitute the rotor winding, and the conductors include openings of the air inlet holes in bottoms of the conductors on a side opposite to a side on which the ventilation channels are formed.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a rotor of a rotary-electric machine,more particularly to a rotor of a rotary-electric machine suitable as,for example, a rotor of a turbine generator in which ventilationchannels for cooling air are formed in conductors constituting a rotorwinding on an end portion of the rotor in an axial direction.

2. Description of the Related Art

A general turbine generator is generally constituted by disposing arotor supported on a rotation shaft so that the rotor faces a stator. Arotor iron core constituting the rotor extends in an axial direction andhas a plurality of slots formed at predetermined intervals in aperipheral direction, and a plurality of conductors forming a rotorwinding are laminated and stored in the slots. The conductors are boundby wedges disposed on outer peripheries of the slots, and the wedges aredesigned so as to hold the conductors even during rotation at a highspeed. A retaining ring is fixedly fitted into an end portion of therotor winding in the axial direction so as to cover the portion via aninsulating cylinder, and this retaining ring retains a centrifugal forceof the conductors.

Additionally, in general, there is not any distinct channel throughwhich cooling air circulates in the vicinity of the conductors under theretaining ring. Therefore, a temperature of this portion rises, but as amethod for preventing the temperature rise of this portion, a method isproposed in which ventilation channels to circulate the cooling air aredisposed in the conductors in a longitudinal direction. As shown in, forexample, FIG. 9, a ventilation channel 41 through which the cooling airflows is formed on the surface side in a conductor 1 along an axialdirection of the conductor and along a peripheral direction halfway. Anair inlet hole 21 which communicates with this ventilation channel 41 tointroduce the cooling air is disposed in a side surface of the conductor1. An exhaust hole 51 to exhaust the cooling air which has flowedthrough the ventilation channel 41 is disposed so as to extend throughthe conductor 1 in a diametric direction. Furthermore, the cooling airwhich has flowed through the ventilation channel 41 to cool theconductor 1 is exhausted from an exhaust port 8 formed in a wedge 7 inFIG. 8.

A plurality of the conductors as shown in FIG. 9 are laminated in amultistage manner to constitute the rotor winding, and the cooling airis introduced into the ventilation channels from the air inlet holeformed in the side surface of the rotor winding. After circulating thecooling air through the ventilation channels to cool the rotor winding,the cooling air is exhausted together from the exhaust hole. This isdescribed in JP-A-63-15644.

Moreover, a second air inlet hole of which an opening is formed in theside surface of the conductor is disposed halfway in the ventilationchannel to improve a temperature distribution of the conductor in thelongitudinal direction. This is described in JP-A-2003-88022.

However, in the above conventional technology (JP-A-63-15644), atemperature of each slot cannot necessarily be lowered efficiently. Thiswill be described with reference to FIGS. 8 and 10. Here, it will bedescribed in accordance with an example of a turbine generator which hasa two-pole field system.

The rotor of the turbine generator usually rotates at a high speed suchas 3000 or 3600 rotations per minute during a rating operation. At thistime, the cooling air for cooling the conductors 1 of the rotor windingis introduced through a gap between a retaining ring 3 and a rotationshaft 2. Here, the cooling air is not introduced in parallel with theaxial direction as viewed from the rotor. The cooling air is usuallyintroduced in such a direction that the air has several rotationcomponents. An air inlet angle of the introduced cooling air in such adirection having the rotation components changes with an amount of thecooling air of the rotor, a structure of a stator side, a flow rate ofthe cooling air on the side of the stator and the like. For example, ifthe generator has a diameter of 1 m and rotates at a speed of 3600rotations per minute, a rotation speed of the conductor 1 isπ×3600/60×1=188 m/s. Supposing that the cooling air does not have anyspeed in the peripheral direction in a space between a stator 5 and arotor 4, cooling air 9 has a relative speed of 188 m/s in the peripheraldirection as viewed from the rotor 4. Since an axial flow speed of thecooling air in this position is usually about 10 to 20 m/s, theintroduced cooling air crosses the axial direction at approximatelyright angles as viewed from the axial direction.

This is shown in detail in FIG. 10. FIG. 10 is an enlarged view in thevicinity of the conductor 1 in FIG. 8 as viewed from a shaft end, andshows a structure in which a plurality of conductors shown in FIG. 9 arelaminated.

In FIG. 10, in the surfaces of conductors 11 to 19, ventilation channels41 to 49 are formed, respectively. In the side surfaces of theconductors, air inlet holes 21 to 29 are formed which introduce thecooling air into the ventilation channels, respectively. The conductorsare turned back at a shaft end portion, and formed into a shapesymmetric with respect to a magnetic pole 80.

Usually, an insulating spacer 70 is disposed in a magnetic pole portionin order to restrict movement of the conductors in the axial direction.In a case where a rotating direction is denoted with reference numeral90, when the cooling air 9 is introduced at a high speed in theperipheral direction as described above, the cooling air 9 does noteasily enter the backside (opposite to the rotating direction 90) of theinsulating spacer 70. That is, in the example of FIG. 10, when thecooling air 9 blows into at a shown angle, a shaded area 100 is a shadow(backside) of the insulating spacer 70, and the cooling air 9 does noteasily enter the backside. That is, there occurs a possibility that anecessary flow rate of the cooling air 9 which enters the air inletholes 21 to 29 positioned in the shaded area 100 cannot be secured. Ifthe air inlet angle of the cooling air 9 is close to 90°, the coolingair 9 might not flow at all. This also applies to air inlet holes 31 to39 disposed in positions symmetrical to those of the air inlet holes 21to 29 with respect to the magnetic pole 80 when the blowing direction ofthe cooling air 9 changes and the air inlet holes 31 to 39 enter theshadow of the insulating spacer 70. As a result, the temperature israised without effectively cooling the conductors, and this results in aproblem that a cooling performance of the rotor winding is notsatisfactory.

BRIEF SUMMARY OF THE INVENTION

The present invention has been developed in view of the above problem,and an object is to provide a rotor of a rotary-electric machine inwhich a cooling performance of a rotor winding has been improved.

To achieve the above object, a rotor of a rotary-electric machineaccording to the present invention comprises: a rotor iron coreextending in an axial direction and having a plurality of slots formedat predetermined intervals in a peripheral direction; a rotor windingconstituted by laminating and storing a plurality of conductors in eachof the slots of the rotor iron core; and a retaining ring which coversand holds an end portion of the rotor winding in the axial direction,the rotor winding held by the retaining ring on an end portion of therotor in the axial direction being provided with ventilation channelswhich are formed in the surfaces of the conductors along a longitudinaldirection and through which cooling air flows, the ventilation channelsbeing provided with air inlet holes which introduce the cooling air andexhaust holes which exhaust the cooling air. The conductors providedwith the ventilation channels which are formed in the surfaces of theconductors along the longitudinal direction and through which thecooling air flows are laminated to constitute the rotor winding, and theconductors are provided with openings of the air inlet holes in bottomsof the conductors on a side opposite to a side on which the ventilationchannels are formed.

In the rotor of the rotary-electric machine according to the presentinvention, the cooling air can be introduced into the conductorsconstituting the rotor winding from the openings of the air inlet holesdisposed in the bottoms of the conductors on the side opposite to theside on which the ventilation channels are formed. Therefore, regardlessof an air inlet angle of the cooling air, the cooling air canefficiently be introduced. There is an advantage that a temperature riseof the conductors is inhibited to improve a cooling performance of therotor winding.

An object to improve the cooling performance of the rotor winding isrealized with a simple constitution without involving any largestructural change.

Other objects, features and advantages of the invention will becomeapparent from the following description of the embodiments of theinvention taken in conjunction with the accompanying drawings.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

FIG. 1 is a partially perspective view showing a part of an end portionof a rotor winding in an axial direction in a turbine generator asaccording to one example of the present invention (Embodiment 1);

FIG. 2 is a partially perspective view showing one example of aconductor employed in the rotor winding of FIG. 1;

FIG. 3 is a partially perspective view showing another example of theconductor employed in the rotor winding of FIG. 1 (Embodiment 2);

FIG. 4 is a characteristic diagram showing comparison of a relationbetween a position of the conductor in a longitudinal direction and atemperature rise of the conductor in the present invention with that ina conventional example;

FIG. 5 is a partially perspective view showing a part of an end portionof a rotor winding in an axial direction in a turbine generatoraccording to a third embodiment of the present invention (Embodiment 3);

FIG. 6 is a partially perspective view showing a part of an end portionof a rotor winding in an axial direction in a turbine generatoraccording to a fourth embodiment of the present invention (Embodiment4);

FIG. 7 is an entirely perspective view showing a partially cut state ofa turbine generator according to one example of the present invention;

FIG. 8 is a partially perspective view showing an end portion of a rotorof FIG. 7;

FIG. 9 is a partially perspective view showing a conventional conductoremployed in a rotor winding of a turbine generator; and

FIG. 10 is a partially perspective view showing a conventional rotorwinding of the turbine generator in which the conductor shown in FIG. 9is employed.

DETAILED DESCRIPTION OF THE INVENTION

[Embodiment 1]

A structure of a turbine generator is shown in FIGS. 7 and 8.

As shown, the turbine generator is generally constituted by disposing arotor 4 supported by a rotation shaft 2 so that the rotor faces a stator5. A rotor iron core 4 a constituting the rotor 4 extends in an axialdirection, and has a plurality of slots 6 formed at predeterminedintervals in a peripheral direction. In the slots 6, a plurality ofconductors 1 forming a rotor winding are laminated and stored. Theconductors 1 are bound to the rotor iron core 4 a by wedges 7 disposedon outer peripheral sides of the slots 6, and the wedges 7 are designedso as to hold the conductors 1 even during rotation at a high speed. Aretaining ring 3 is fixedly fitted into an end portion of the rotorwinding in the axial direction via an insulating cylinder so as to coverthe end portion, and this retaining ring 3 retains a centrifugal forceof the conductors 1.

Additionally, in general, there is not any distinct channel throughwhich cooling air circulates in the vicinity of the conductors 1 underthe retaining ring 3. Therefore, a temperature of this portion rises,but as a method of reducing the temperature rise of this portion, amethod is proposed in which ventilation channels to circulate thecooling air are disposed in the conductors in a longitudinal direction.As shown in, for example, FIG. 9, a ventilation channel 41 through whichthe cooling air flows is formed in the surface of the conductor 1 so asto extend along an axial direction of the conductor and along aperipheral direction thereof halfway. An air inlet hole 21 whichcommunicates with this ventilation channel 41 to introduce the coolingair is disposed in the side surface of the conductor 1. An exhaust hole51 to exhaust the cooling air which has flowed through the ventilationchannel 41 is disposed so as to extend through the conductor 1 in adiametric direction. Furthermore, the cooling air which has flowedthrough the ventilation channel 41 to cool the conductor 1 is exhaustedfrom an exhaust port 8 formed in a wedge 7.

FIG. 1 shows the end portion of the rotor winding in the axial directionin the turbine generator as one example of a rotor of a rotary-electricmachine according to the present invention.

In the same manner as a conventional rotor winding, the rotor windingshown in FIG. 1 is constituted by laminating and storing a plurality ofconductors 11 to 19 in slots of a rotor iron core extending in an axialdirection and having a plurality of slots formed at predeterminedintervals in a peripheral direction.

Among the conductors, one conductor 11 is shown in FIG. 2. As shown inthe drawing, in the conductor 11, a ventilation channel 41 through whichcooling air 9 flows is formed along an axial direction on the side ofthe surface of the conductor 11 and along a peripheral directionhalfway. Furthermore, in the bottom of the conductor 11 on a sideopposite to a side on which this ventilation channel 41 is formed, thereis formed an opening of an air inlet hole 21 extending through thechannel in a diametric direction to introduce the cooling air 9 into theventilation channel 41. On the other hand, on the side of theventilation channel 41 opposite to the side on which the air inlet hole21 is formed, an exhaust hole 51 to exhaust the cooling air 9 which hasflowed through within the ventilation channel 41 is disposed so as toextend through the channel in the diametric direction.

Moreover, when a plurality of conductors 12 to 19 having a constitutionsimilar to that of this conductor 11 are laminated in the diametricdirection, the ventilation channel is secured by covering the groovewith a plane of the upper conductor, in which the ventilation channel isnot formed. Furthermore, the air inlet holes and the exhaust holescontinuously extend in the diametric direction to communicate with theventilation channels of the conductors, respectively, thereby securingthe holes.

With such a constitution of the present embodiment, the cooling air 9 isintroduced into the rotor winding from openings of air inlet holes 21 to29 formed in the bottoms of the conductors 11 to 19 on a side oppositeto a side on which ventilation channels 41 to 49 are formed. Therefore,regardless of an air inlet angle of the cooling air 9, the air inletholes 21 to 29 are not disposed behind (on the backside of) aninsulating spacer 70. Accordingly, the cooling air 9 can effectively beintroduced into the air inlet holes regardless of the speed in aperipheral direction. Therefore, the cooling air 9 which has entered theair inlet holes 21 to 29 passes through the ventilation channels 41 to49 and is exhausted from exhaust holes 51 to 59. In consequence, atemperature rise of each conductor is reduced to improve a coolingperformance of the rotor winding.

It is to be noted that it is preferable that a circulation area of theair inlet holes 21 to 29, the exhaust holes 51 to 59 and the like is setto be larger than a total circulation area of the ventilation channels41 to 49.

[Embodiment 2]

FIG. 3 shows another example of a conductor employed in a rotor windingaccording to the present invention. In the shown example, in a middle ofa ventilation channel 41 of a conductor 11 shown in FIG. 2, a second airinlet hole 31 is disposed in a bottom of the conductor on a sideopposite to a side on which the ventilation channel 41 is formed. Aplurality of conductors formed in such a manner are laminated in adiametric direction to constitute a rotor winding.

Even with such a constitution, needless to say, the above-describedeffect is achieved. Moreover, since a plurality of air inlet holes aredisposed, a temperature distribution of the conductors in a longitudinaldirection can arbitrarily be changed.

FIG. 4 shows an example of a temperature rise in the position of eachconductor in the longitudinal direction in a case where the conductor inFIG. 3 is used, the abscissa indicates the position of the conductor inthe longitudinal direction, and the ordinate indicates the temperaturerise of the conductor. As apparent from the drawing, it is seen that ascompared with a conventional example (JP-A-2003-88022) in which theopenings of the air inlet holes are disposed in the side surfaces of theconductors, a peripheral speed of incoming cooling air is high and theopenings are obstructed by a structure such as an insulating spacer, inthe present embodiment, the cooling air enters the air inlet holes fromthe openings in the bottoms of the conductors without being wasted.Therefore, a cooling flow rate increases over the whole length of eachconductor in the longitudinal direction, and the temperature rise in thelongitudinal direction of the conductor is reduced.

It is to be noted that in this example, there has been described anexample in which two air inlet holes are disposed in one conductor, buta further air inlet hole may be disposed, or needless to say, aplurality of exhaust holes may be disposed in the conductor. Moreover,it is possible to omit an exhaust hole 51 of the lowermost conductor 11having its bottom exposed to the cooling air.

[Embodiment 3]

FIG. 5 shows a third embodiment of the present invention. In thisembodiment, openings of air inlet holes 21 to 26 are disposed in bottomsof conductors on a side opposite to a side on which ventilation channels41 to 46 are formed. Moreover, the air inlet holes continuously extendin a diametric direction to communicate with end portions of theventilation channels 41 to 46 formed in the surfaces of the conductorsalong a peripheral direction. Furthermore, in axial-direction endportions of the ventilation channels 41 to 46 formed in the surfaces ofconductors 11 to 16 along an axial direction, the end portion in a lowerpart (conductors 11 to 13) of a rotor winding in a laminating directionof the conductors 11 to 16 is formed to extend longer than that in anupper part (conductors 14 to 16) of the rotor winding. As to exhaustholes which exhaust cooling air 9 flowing through the ventilationchannels 41 to 46, there is formed a path (exhaust holes 55, 56) whichcommunicates with the end portions of the ventilation channels 44 to 46in the axial direction in the upper part of the rotor winding in thelaminating direction of the conductors. Independently of the path, thereis disposed a path (exhaust holes 62 to 66) which communicates with theend portions of the ventilation channels 41 to 43 in the axial directionin the lower part of the rotor winding in the laminating directions ofthe conductors and which extends through the conductors 12 to 16.

With such a constitution of the present embodiment, needless to say, aneffect similar to that of the embodiment described above with referenceto FIG. 1 can be achieved. Moreover, since two independent channels (theexhaust holes 54 to 56 and 62 to 66) are disposed, the cooling airhaving an appropriate flow rate can be circulated through upper andlower turns of the conductors, respectively, and this facilitates atemperature control. As a method of controlling the cooling air, acirculation area of the ventilation channel for each conductor turn maybe changed, or a length of the ventilation channel in the longitudinaldirection of the conductor may be changed. Alternatively, the number ofthe turns of the conductor accepted by one hole may be changed.

It is to be noted that any exhaust hole does not have to be disposed inthe lowermost conductor having its bottom exposed to the cooling air.When a cooling effect is sufficient, a plurality of grooves of theconductors may be omitted.

[Embodiment 4]

FIG. 6 shows a fourth embodiment according to the present invention. Inthis embodiment, ventilation channels 41 to 46 which are formed in thesurfaces of conductors 11 to 16 along a longitudinal direction andthrough which cooling air 9 flows are formed so as to extend along anaxial direction on the side of the surfaces of the conductors and alonga peripheral direction halfway in an upper part (conductors 14 to 16) ofa rotor winding in a laminating direction of the conductors 11 to 16. Ina lower part (conductors 11 to 13) of the rotor winding in thelaminating direction of the conductors 11 to 16, the ventilationchannels are formed in an only axial direction on the side of thesurfaces of the conductors. Moreover, the ventilation channels include:the first air inlet holes 21 to 26 openings of which are disposed inbottoms of the conductors on a side opposite to a side provided with theventilation channels 41 to 46 and which continuously extend in adiametric direction to communicate with end portions of the ventilationchannels 44 to 46 formed along the peripheral direction on the side ofthe conductor surfaces; and, in the lower part (conductors 11 to 13) ofthe rotor winding in the laminating directions of the conductors 11 to16, second air inlet holes 31 to 33 of which openings are formed in thebottoms of the conductors on the side opposite to the ventilationchannels 41 to 46 and which continuously extend halfway in the diametricdirection to communicate with end portions of the ventilation channels41 to 43 in the axial direction, the channels being formed in thesurfaces of the conductors 11 to 13 in the only axial direction.Furthermore, as to exhaust holes which exhaust the cooling air 9 flowingthrough the ventilation channels 41 to 46, there are formed: a path(exhaust holes 55, 56) which communicates with the other end portions ofthe ventilation channels 44 to 46 in the axial direction, the channelsbeing formed along the axial direction and the peripheral direction, inthe upper part (conductors 14 to 16) of the rotor winding in thelaminating direction of the conductors; and, in the lower part(conductors 11 to 13) of the rotor winding in the laminating directionsof the conductors, another path (exhaust holes 62 to 66) whichcommunicates with the other end portions of the ventilation channels 41to 43 in the axial direction, the channels being formed in the onlyaxial direction, and which extends through the conductors 12 to 16, thepaths being independent of each other.

With such a constitution of the present embodiment, needless to say, aneffect similar to that of the embodiment described above with referenceto FIG. 1 can be achieved. Moreover, two channels (the air inlet holes21 to 26 and 31 to 33) are disposed in a longitudinal direction on anair inlet side, two channels (exhaust holes 55 and 56 and 62 to 66) arealso disposed on an air exhaust side, and the ventilation channels 44 to46 of the upper conductors 14 to 16 are constituted completelyindependently of the ventilation channels 41 to 43 of the lowerconductors 11 to 13. Therefore, a temperature control is furtherfacilitated as compared with the embodiment shown in FIG. 5. It is to benoted that any exhaust hole does not have to be disposed in thelowermost conductor having its bottom exposed to the cooling air.

According to the present invention, since a cooling medium flow ratedistribution in an axial direction of a winding for each slot isimproved, homogenization of a temperature rise of a rotor conductor andreduction of a temperature rise can be achieved. It is to be noted thatin the present invention, a power generator has been described as anexample, but the present invention is broadly applicable to arotary-electric machine such as a motor.

It should be further understood by those skilled in the art thatalthough the foregoing description has been made on embodiments of theinvention, the invention is not limited thereto and various changes andmodifications may be made without departing from the spirit of theinvention and the scope of the appended claims.

1. A rotor of a rotary-electric machine comprising: a rotor iron coreextending in an axial direction and having a plurality of slots formedat predetermined intervals in a circumferential direction; a rotorwinding constituted by laminating and storing a plurality of conductorsin each slot of said rotor iron core; and a retaining ring which coversand holds an end portion of said rotor winding in the axial direction,and said rotor winding being provided with ventilation channels on thesurfaces of said conductors along a longitudinal direction and throughwhich cooling air flows, said ventilation channels being provided withair inlet holes which introduce said cooling air and exhaust holes whichexhaust the cooling air, wherein said ventilation channels which areformed in the surfaces of said conductors along the longitudinaldirection and through which cooling air flows are formed along the axialdirection and along the circumferential direction halfway in an upperpart of said rotor winding in a laminating direction of said conductors,said ventilation channels are formed in the surfaces of said conductorsin only the axial direction in a lower part of said rotor winding in thelaminating direction of said conductors, said ventilation channelsinclude: first air inlet holes of which openings are formed in bottomsof said conductors and which continuously extend in a diametricdirection to communicate with end portions of said ventilation channelsformed in the surfaces of said conductors along the circumferentialdirection; and second air inlet holes of which openings are formed inthe bottoms of said conductors and which continuously extend halfway inthe diametric direction to communicate with end portions of saidventilation channels in the axial direction, said ventilation channelsbeing formed in the surfaces of said conductors in only the axialdirection, in a lower part of said rotor winding in the laminatingdirection of said conductors, and as the exhaust holes which exhaust thecooling air flowing through said ventilation channels, a path whichcommunicates with the end portions of said ventilation channels in theaxial direction, said ventilation channels being formed along the axialdirection and the circumferential direction, in the upper part of saidrotor winding in the laminating direction of said conductors; andanother path which communicates with the other end portions of saidventilation channels in the axial direction to extend through saidconductors, the channels being formed in only the axial direction, inthe lower part of the rotor winding in the laminating direction of theconductors, said paths being arranged independently of each other. 2.The rotor of the rotary-electric machine according to claim 1, whereinsaid exhaust hole is omitted from said conductor positioned in alowermost part of said rotor winding.